H2O-CaCl2 equilibrium phase diagram. Phases at equilibrium for the chemical system H2O-CaCl2 are shown as a function of chemical composition (mole percent CaCl2) and temperature at 1 atmosphere pressure. There are six stoichimetric solid phases. Three of the solids, ice, antarcticite (CaCl2.6H2O), and sinjarite (CaCl2.2H2O), occur naturally and have mineral names. Each of the six solids melts incongruently, except for H2O and CaCl2. CaCl2 melts congruently at 772°C. Peritectic and eutectic compositions and temperatures are shown on the axes. There is a chaotectic point between steam and CaCl2.H2O at 178°C. Data sources for this diagram can be found in Brady (2009).